This invention relates to the art of adhering a magnet to a substrate, and more particularly, the present invention relates to a coating composition having a random magnetic pole alignment able to be directly applied to a substrate, dried, and then aligning the magnetic poles such that the coating composition has a non-random magnetic pole alignment (aligned magnetic poles).
Traditionally, magnet compositions, made up of magnetic or magnetizable materials, (e.g., ferromagnetic material) and flexible resins have been used to form conventional flexible magnets by using several methods including compaction molding, injection molding, and extrusion molding.
The various methods used to produce flexible magnets include several complex, cost prohibitive steps. For instance, in compaction molding, a compound is packed in a press mold and compacted at a room temperature so as to form a green body. Subsequently, when the binding resin is a thermosetting resin, the resin is hardened, whereby a magnet is obtained. Extrusion molding is a method in which heated molten compound extruded from an extruder die is solidified by cooling and then cut at a desired length, whereby a magnet is obtained. In injection molding, a compound, which has been heated and molten to exhibit sufficiently high fluidity, is poured into a mold so as to form a magnet of a desired shape. Once the magnets are produced and readied for a particular substrate, there are several additional steps involved in adhering the magnet and the substrate together. For these reasons, it is desirable to apply a magnetizable coating directly to the substrate in one step.
In U.S. Pat. No. 3,503,882, Fitch disclosed a paint composition containing iron powder and an epoxy ester resin with an emulsifiable polyethylene wax and an organophilic alkyl ammonium bentonite dispersed in a paint hydrocarbon solvent when applied to a substrate and dried, a surface to which magnetic symbols will adhere and which will accept chalk markings. The iron powder employed in the oil-based paint formulation was rather coarse, at least 100 to 200 mesh, with over half preferably over 200 mesh, and comprising from about 70 to about 85% by weight, based on the combined weight of the iron powder and epoxy ester resin. Thus, the product was so coarse that it was brushed on, rather than rolled or sprayed, and fumes from the paint solvent are currently regarded as toxic.
In U.S. Pat. No. 5,587,102, Stem and Treleaven disclosed a magnetic latex paint composition comprising a carrier, particulate magnetically permeable material, a binder and a thickening agent having thixotropic and viscosity characteristics such that the paint composition has high viscosity characteristics when stationary, and low viscosity when shear forces to the paint as it is applied to a wall surface. Particulate iron no smaller than 350 mesh was employed with synthetic clay as a thickening agent to keep particles in suspension. Thus formulated, drying retarders were necessary so that a smooth surface after paint application could be achieved without lap marks. When the paint dried, magnetic objects could be mounted on the surface, held in place by the interaction with the magnetically permeable material.
While previous patents teach of magnetic paints and coatings, there fails to be a suitable magnetic coating composition capable of being suitably magnetized once dried on the substrate. The present invention provides a magnetic coating composition which improves upon the art.
It is an object to improve magnetic coating compositions.
It is yet another object to provide a relatively thin coating composition having magnetic properties which is inexpensive.
It is yet another object to provide a relatively thin coating composition having magnetic properties which is easy to apply to a substrate.
It is yet another object to provide a relatively thin coating composition having magnetic properties which includes high solids content while maintaining its flexibility.
The present invention includes coating composition having magnetic properties for application to a substrate. The coating composition includes a plurality of ferromagnetic particles having a random magnetic pole alignment and a binder adhesive capable of suspending the ferromagnetic particles. The binder adhesive is capable of adhering in a substantially thin film to the substrate. The binder adhesive allows for manipulation of the ferromagnetic particles to a non-random magnetic pole alignment after the ferromagnetic particles have dried in the binder adhesive on the substrate.
The coating composition having magnetic properties allows for the wet coating composition, having a simplistic binder adhesive formulation, to contain a relatively high percentage (such as 90-98% by weight of the dry coating composition) of ferromagnetic particles without the occurrence of clumping. Another advantage to a coating composition having magnetic properties is a user""s ability to reasonably determine the degree of magnetization that he or she wishes to give the coating composition once dried on the substrate.
xe2x80x9cMagnetxe2x80x9d is a body, as a piece of iron or steel, that possess the property of attracting certain substances, as iron; a thing that attracts.
xe2x80x9cMagnetizexe2x80x9d is to make a magnet of; impart the properties of a magnet to; to exert an attracting or compelling influence.
xe2x80x9cMagnetic pole alignmentxe2x80x9d as used herein means manipulating the magnetic poles of a ferromagnetic material.